Research: consequences of dispersal

What impact does dispersal (particularly individual differences in dispersal) have at the population level in terms of structure, dynamics, viability and spread?

Dispersal is an individual behavior that can have big consequences at the population level. We show that the dispersal strategies favored by individuals typically have a negative impact on population size and connectivity. We also show that individual differences in dispersal can either increase or decrease population connectivity (compared to a population of identical individuals), depending on the average dispersal distance. (Shaw, Jalasvuori & Kokko 2014)

Individual dispersal behaviors also have a big impact on how fast a population will spread (e.g. for invasive or reintroduced species). We show that increasing sex differences in dispersal can either speed up or slow down the rate of spread, depending on the mating system (Miller, Shaw, Inouye & Neubert 2011). We show that limiting the time available for mating causes a demographic Allee effect which can slow or prevent invasions, and that sex-based asymmetries in life history amplify these effects (Shaw, Kokko, Neubert in press). We also show that simple internal population dynamics (density-dependent dispersal + Allee effects) can generate fluctuations in invasion speed, in the absence of any environmental heterogeneities (Sullivan, Li, Miller, Neubert, Shaw 2017).

We are currently studying the dispersal of Minnesota prairie plant species, in a project funded by the Minnesota Legislative-Citizen Commission on Minnesota Resources (﻿﻿LCCMR﻿﻿). Postdoc Lauren Sullivan is leading this work, and collaborating with Allison, and Dave Moeller with help from Jordan and Dylan. We are using DNA parentage analysis of GPS-located individuals in order to measure how far offspring are moving from parents. Using this dispersal information we will determine the connectivity of the current grassland fragments (both restored and remnant) in Northwest Minnesota. Read more on our project website. and in the CBS blog post.

Next steps

What is the relative importance of sex-specific versus age-specific dispersal? (with Neubert)